Raipur: A policeman was killed and his five colleagues were injured, along with 19 prisoners on Saturday when a blast triggered by the Maoists ripped through their vehicle in the insurgency-hit Bastar region of Chhattisgarh, police said.

"All the 25 people seated in the vehicle sustained serious injuries but the condition of three policemen and 11 prisoners is critical," Additional Director General of Police (Maoist Operations) Ram Niwas said to a news agency.

The attack took place on a bridge on National Highway No.30 in the newly-formed Kondagaon district, some 210 km south from state capital Raipur.

The blast ripped through the vehicle carrying 25 people, including 19 prisoners, who were returning to Bastar district headquarters Jagdalpur from Kondagaon after being presented in a local court, police here said.

Niwas said it was a powerful blast.

The local police officials admitted that the attack was "a fallout of serious security lapse". The critically injured would be taken to Raipur for medical treatment.

A police official in Jagdalpur said the attack "may be a case of mistaken identity" as the jail vehicle looked similar to the vehicle used by police and paramilitary forces in the Bastar region.(Agencies)